Tool for forming taper-holes



A. E. SIMPSON.

TOOL FOR FORMING TAPER HOLES.

APPLICATION FILED JULY 28,1920.

Patented 001;. 5,1920.

HLBERT SIMPSON ATENT OFFICE.

ALBERT EDWARD SIMPSONfOF BURY, ENGLAND.

r001. r012. romume mrmanoms.

Specification of Letters Patent.

Patented Oct. 5, 1920.

Application fi led July 28, 1920. Serial No. 399,484. Y

To all whom it may concern:

Be it known that I, ALBERT EDWARD SIMPSON, a subject of the King of Great- Britain, residing at 80 Heywood street, Bury, in the county of Lancaster, England, have invented a new and useful Improved Tool for Forming Taper Holes, of which the following is a specification.

Myinvntion relates to combined drilling and reaming tools for forming taper holes at one operation in which the end of the tool is formed to start, and continue to form, the hole and constitutes the drilling portion of the said tool, and the following portion threads extendin is tapered and constitutes the reaming ortion of the said tool. In tools, of the a oresaid kind, it has been proposed to form across the whole of the surface between t e spiral grooves, or flutes, whereby a number of stepped cutting points are formed atthe leading, or cutting, edges of the reamer portion of the tool and this invention has for its object to provide an improved tool of this kind whereby friction on the work and the torsional strain set up in the tool when in use are considerably reduced and the danger .of the said tool breaking is consequently minimized. This,

according to my invention, is effected by forming a number of stepped cutting points on the leading, or cutting, edges only of the reaming portion of the tool. I r

The accompanying drawin illustrates sufficient portions of tools ma e in accordance with this invention, Figure 1 showing the invention a plied to a spiral'tool and Fig. 2 showing it applied to a fiat tool.

In both figures the stepped cuttin points hereinbefore referred to are marke a, and the spaces, or clearances, between the cut ting points which avoid, as much as possible, non-cutting frictional action against the sides ofthe hole, are marked 6.

The tool in each case is shown as having the end 0 formed to start, and continue to form, the hole, the following part of the toolv forming the taper and acting as a reamer.

The following is a further explanation of how the toolmay be made in comparison with the making of an ordinary twist drill.

The drill is made with a taper, say 1 for example in 48 which is the standard for taper ,pins.

The distortion which results from the hardening process is rectified, in the case of ordinary drills, by grinding the land portion of the drill, by means of an abrasion wheel, while the drill rotates on its axis. When grinding the taper drill at this final operation, the eriphery of the abrasive wheel is made of such shape as to form cutting points on the leading edges only of the drill in accordance with this invention. Supposing the drill to make, for instance, eight rotations for each inch which the abrasive wheel travels in a longitudinal direction relatively to the axis of the drill, eight ratchet-shaped teeth are formed per inch in the length of the drill, these teeth being portions of a screw-thread.

What I claim is A combineddrilling and reaming tool, of the kind aforesaid, for forming taper holes, the said tool being formed with a number of stepped cutting points confined to the leading, or cutting, edges only'of the reaming portion so as to reduce non-cutting frictional contact with the sides of the hole;

ALBERT EDWARD SIMPSON.

Witnesses:

ERNALD S. MOSELEY,

Gnonon WEAVER. 

